Chromatography has been in widespread use for the fractionation, separation and analysis of biological and/or ecological materials. Various chromatographic techniques in use have included adsorption chromatography, ion exchange chromatography, gel permeation chromatography, gas chromatography, paper chromatography and thin-layer chromatography. In the ecological field, particularly, several of the same or different chromatographic techniques are often required to separate the complex mixtures of organic compounds encountered in laboratory samples to be analyzed.
It has occasionally been found that certain compounds or classes of compounds, when present in unknown mixtures, interfere with the normal separation and analysis of bio-affecting agents anticipated as being components of the mixture. For example, it has been very troublesome to completely separate toxic, planar polychlorinated biphenyl (PCB) components from mixtures which include other aromatic industrial chemicals together with pesticides, herbicides, natural biological fluids and fatty tissue. Moreover, the toxic, non-planar chlorinated aromatic compounds found as pollutants in the environment, namely, the pesticides KEPONE (chlordecone) and mirex, are typically difficult to chromatographically fractionate when found in admixture with certain planar components. Such non-planar pollutants are not retained by activated charcoal or other conventional adsorbents utilized in column chromatography. Separation and analysis has, however, been achieved by means of molecular size exculsion, or gel permeation, polymers. These materials are cross-linked copolymer gels which function like sponges on a micro scale. The size of the gel pores are controlled by the degree of cross-linking so that only certain molecular sizes can be retained by the gel while all other compounds of larger molecular size are excluded.
The chlorine substituted naphthalenes, dibenzodioxins and dibenzofurans have been found to be very hazardous to the environment because of their high toxicity to fish and animal life at concentrations as low as 1 ppm. These planar polynuclear aromatic compounds are preferentially adsorbed by passage through adsorption columns containing activated charcoal powders, often in admixture with dispersive agents or filter aids such as sand, magnesia, diatomaceous earth, and glass powder. Polyurethane foam has also been employed as an inert support for the carbon material in such columns. Such adsorbents are more fully discussed in U.S. Pat. Nos. 4,102,816 and 4,110,344 which issued on July 25 and Aug. 29, 1978, to Stalling et al. However, such supports, dispersive agents, and filter aids do not enhance chromatographic separation and, consequently, a minimum of two columns are normally required for analyses where both planar and non-planar aromatics are suspected as being present.